Blow-molded plastic bottles for containing liquids at elevated pressures are known and have found increasing acceptance. Such containers are accepted particularly in the beverage industry as disposable containers for use with effervescent or carbonated beverages, especially carbonated soft drinks. These plastic containers can reliably contain carbonated beverages generating internal pressures as high as 100 psi or more and can be inexpensively manufactured. Typically, these plastic bottles have a cylindrical shape which reliably contain carbonated beverage products, can be easily handled, can be inexpensively manufactured, and have stability when filled and unfilled. Such containers have most frequently been manufactured from plastic materials such as polyethylene terephthalate (PET) by, for example, blow molding a portion of PET into a mold formed in the shape of the container. The biaxial expansion of PET by blow molding imparts rigidity and strength to the formed PET material, and blow molded PET can provide economically acceptable wall thicknesses, with clarity in relatively intricate designs, sufficient strength to contain pressures up to 100 psi and more, and resistance to gas passage that may deplete contained beverages of their carbonation.
One problem in plastic container design is the propensity of PET to succumb to the deleterious effects of stress cracking and crazing, which is manifested as almost imperceptible streaks in the plastic, but ultimately can become complete cracks due to stress and other environmental factors. Relatively unstretched portions of a plastic container that have low degrees of crystallinity due to the lack of biaxial expansion, such as the central bottom portion, are particularly susceptible to crazing and stress cracking. The relatively unstretched central portion of the container bottom is also frequently provided with a plurality of depending feet that are formed with distention-resistant but stress concentrating areas, and the composite effect on such areas of stress and strain due to the internal pressure of the container and external environmental factors can lead to crazing, stress cracking and container bottom failure.
One commercial cylindrical beverage container that seeks to avoid such problems is formed with a full hemispherical bottom portion and provided with a separate plastic base member fastened over the hemispherical bottom portion to provide a stable base for the container. Such containers are in common use for large multi-liter containers for carbonated beverages, even though the provision of a separate plastic base member imposes increased container height, and increased manufacturing and material costs for each container. Another commercial cylindrical beverage container that seeks to avoid such problems includes a “champagne” type base having concave, or “domed” eversion-resisting central bottom portions merging with the cylindrical container sidewalls at an annular ring which forms a stable base for the container. The central domed portion of a champagne-based plastic container generally creates clearance for the gate area of the container which is intended to resist deformation due to the internal pressure of the container but is sensitive to stress cracking. However, containers with champagne bases require a greater wall thickness in the base portion to resist the distending and everting forces of the internal pressure and form stress concentrations at the annular base-forming transition between the concave central bottom portion and cylindrical sidewall that are prone to stress cracking and rupture when the container is dropped.
More recently, hemispherical bottom portions and concave champagne-like bottom portions have been combined, in which a plurality of feet are formed in the bottom of a blow molded container. These designs frequently seek eversion-resistant concave central bottom portions formed by a plurality of surrounding feet that are interconnected by a plurality of generally downwardly convex hemispheric rib portions. Many of such container designs providing footed bottles are in commercial usage. Such container designs are still subject, in the absence of relatively thick bottom wall portions, to distention of their concave central portions due to high internal pressures that can create “rockers” and significantly increased interior container volume with lower fluid levels, all of which are unacceptable to purchasers. Efforts to increase the eversion and distention resistance of the concave bottom portions of such footed containers with thinner bottom wall thicknesses have frequently led to bottom portions including small radii of curvature and discontinuous and abrupt transitions between adjoining surfaces that provide stress concentration, crazing and stress cracking sites. Many of these problems have been overcome by various bottom configurations such as illustrated in U.S. Pat. Nos. 4,120,135; 4,978,015; 4,939,890; 5,398,485; 5,603,423; 5,816,029; 5,826,400; 5,934,024; and 6,276,546. The bottles disclosed in these patents are incorporated herein by reference to illustrate some examples of the type and shape of bottles that can be used in the present invention.
Much of the plastic bottle design has been directed to the carbonated bottle industry. However, the non-carbonated beverage market such as water, sport drinks, fruit drinks and the like has continued to grow. It is not uncommon that plastic bottles originally designed for carbonated beverages are used for non-carbonated beverages. However, the use of these plastic bottles has been problematic, especially during the bottling of the non-carbonated beverage. The gas in carbonated beverage exerts a force on the interior of the bottle, thus resisting the deformation or collapse of the base of the bottle during the capping of the bottle. As a result, the base and walls of the plastic bottle can be made of a thinner material, which is a significant cost savings to the manufacturer. The absence of gas in non-carbonated beverages has resulted in increased deformation and/or damage of base of the plastic bottle during the bottling process. In order to address this problem, increased wall thickness for the sidewalls and base of the plastic bottle has been used. Although the increased wall thickness of the plastic bottle reduces the incidence of deformation and/or damage of the base of the plastic bottle during the bottling process, the increased wall thickness translates into increased material costs. Plastic bottles or containers that include a plastic base attachment have also been used to address this problem. However, the use of the plastic base attachment also increases the cost of the bottle or container. Bottling manufactures that bottle both carbonated and non-carbonated beverages must now maintain additional inventory of various bottle or container configurations and thicknesses.
Machines in the bottling industry for filling containers or capping containers after being filled are well known in the prior art. As defined herein, such machines are collectively referred to as bottling machines. Reference may be had to U.S. Pat. Nos. 5,934,042; 5,816,029; 5,732,528; 4,939,890; 4,624,098; and 4,295,320 which are incorporated by reference herein for a description of applications for conventional type bottling machines. Such machines will not be described in detail in this specification.
Generally, a capping and/or filling apparatus includes a rotatable star wheel mechanism for moving the containers through the machine. The star wheel generally includes a mechanism for supporting the container which is generally arranged about the periphery of the star wheel. An infeed mechanism or conveyor is utilized to bring the containers to an entry point of the star wheel, and an outfeed mechanism or conveyor is similarly mated to the rotatable star wheel mechanism to transfer the capped (or filled) containers from an exit point of the star wheel. A stationary rear guide extending generally between the entry and exit points is generally spaced radially outwardly from the neck support assembly on the rotatable star wheel. This rear guide functions to retain the containers in the individual pockets of the neck support assembly as the star wheel rotates. In a conventional capping apparatus, a turret capper head is directly over the capper star wheel and moves in synchronous rotation with the capper star wheel. In a bottle filling apparatus, a filling head is located above the capper star wheel. Either of the capper head or the filling head is driven axially downward at pre-determined periods of time to place a tightened cap onto the container or to place product within the bottle. Each capper head generally employs a clutch mechanism whereby the capper head is rotated and driven axially downward at a predetermined force and torque to tighten the cap on the container.
Within a bottling plant or facility, a single capping or filling machine is used to fill or cap many different sized containers. In the soft drink industry such size container can include a 12-oz bottle, a 20-oz bottle, a 1-liter bottle, a 2-liter bottle, or others. Positive control of the containers throughout the machine is typically maintained by holding the containers by the neck. Thus, based upon a predetermined control height, all the containers will be guided, and/or be partially or fully suspended throughout the filling or capping process by the container neck flange. Normally, the container will be rested on or be suspended above the normal wear surface. Mounted on the basic shaft of the bottling machine is a hub which supports the mounting plate and star wheel thereon. As the shaft is rotated, the hub rotates the star wheel, thus moving the containers through the machine to accomplish the capping and filling process. Smaller star wheels include and neck support assemblies integral with the hub. Larger star wheel assemblies include neck guide assemblies mounted on the star wheel. Each neck guide assembly has fingers extended therefrom and guides and/or supports the neck of the container.
In order to retain the control height for different sized containers, each container requires a different size and/or shape neck support bracket and lower body guide support for the sidewall of the container. Thus, in each instance where the container size to be run is changed, it is necessary to changeover different aspects of the bottling machine including those portions of the machine which are specific to the particular container size being run on the line. In a bottling plant, such a changeover requires the use of skilled labor to remove the equipment which is specific for a particular size container and replace it with substitute equipment which is specific for a different size container. Thousands of containers pass through a bottling machine each hour. Maintaining this volume is very important to meet both consumer and industry demands as well as plant capacity. As such, the down time associated with a changeover to different size containers is a significant loss both in dollars and productivity due to reduced output capacity, idle manpower and the skilled work force required to complete a changeover. In order to address this problem, a modified container guide was developed and is disclosed in U.S. Pat. No. 5,732,528 which is incorporated herein by reference. U.S. Pat. No. 5,732,528 discloses an improved container guide system for a bottling machine, which includes a redesigned star wheel and rear container guides that enable the body guide, or body star, on the star wheel and the sidewall guide on the rear container guide to be capable of quick adjustment without the necessity of removing and reinstalling different guides for different sized bottles. Changeover mainly requires depressing a button on each guide to release an adjustable locking mechanism and to slide the guide along a positioning rod to a desired new position. A positioning block located on the guides holds the adjustable locking mechanism and effectively moves the body guide and/or sidewall guide to its new position where the button is released to lock the guide in place. The easy adjustment also allows for quick and easy removal of the guide and replacement with another guide having the size requirements desired. This improved container guide system significantly reduces the down time of a bottling line due to a changeover. No tools are needed to effect the changeover as it relates to container guides, thus a machine operator is capable of depressing the button for releasing and sliding the body guide, or body star, on the star wheel or the sidewall guide on the rear container guide to a second position where the button is released and the guide is locked into place. The improved guide system also reduces the number of parts necessary to effect a changeover on a bottling line and provides a positive adjustable control guide once the initial modifications to install the invention are made to the bottling machine.
With respect to the cap or the closure, for years, the crown was the dominant closure employed on containers and is still in use today in the beer industry. The crown closure eventually was partially replaced by caps or closures commonly called “roll-on” caps. This type of closure comprised a cap shell of aluminum which was inserted over the threaded neck of the container and then secured in place by rolling threads in situ into the walls of the cap shell. Capper heads which performed the rolling operation typically exerted downward forces of up to 500 pounds onto the neck of the container. This force, of course, was transmitted to the base of the container and thereat developed a sufficient frictional force with the capper star wheel base to prevent container rotation during the capping process. Over time, the roll-on cap was partially replaced with plastic or metal locking type, threaded caps. In the beverage industry, threaded safety caps have a frangible connection at the cap base thereof which will herein be referred to as a “lock band”. In the case of a metal cap, the capper heads simply crimped the lock band about the container neck portion beneath the lowermost thread. In the case of a plastic cap, heat is applied to the lock band of the cap after the cap is tightened onto the filled container and then shrunk to the neck of the container. Plastic caps with heated lock bands can be applied to either plastic or glass containers. In the plastic cap application, the force of the capper head is generally reduced to a downward thrust of about 50–60 pounds. This force is not sufficient to generate a sufficient frictional force at the base of the container to prevent the container from rotating in the pocket of the capper star wheel. Container rotation in the capper pocket prevented adequate cap tightening. Accordingly, several different concepts have been employed to prevent container rotation for plastic cap applications. For example, the container was shaped with a wedge sidewall configuration and the transfer mechanisms between the various star wheels was modified to feed the containers into configured pockets. Additionally, a high friction material such as polystyrene was applied to the bottom of the container, especially for glass bottles, so as to better grip the base of the capper star wheel and enhance the frictional, anti-rotation force. Such modifications, while functional, were not acceptable. The consuming public did not accept configured containers. Adding friction material to the container materially increased its cost, and its effectiveness was diminished in the event the base of the capper star wheel became wet or was subjected to oil, both of which are common occurrences in the operation of a bottling plant. U.S. Pat. No. 4,624,098, which is incorporated herein by reference, disclosed the use of a belt to urge the container against the rear guide, thus increasing the friction between the side of the container and the rear guide which, when added to the frictional force at the base of the container, helped to prevent container rotation during the tightening of the cap. This capping design has proven acceptable in capping applications where the downward force exerted on the container head from the capping head is as low as 50–60 pounds.
More recently, plastic, threaded safety caps or closures have been developed which do not require the application of heat to set or position the lock band. By tapering the bottle neck beneath the lowermost thread and also tapering the edge of the lock band, the lock band simply snaps in a locking position vis-a-vis the tapered fit when the cap is tightened to a predetermined position. This position occurs when the axial downward force on the cap from the capper head is about 15–20 pounds. This low capper force makes retention of the container within the pocket very difficult, even with the use of very strong elastic bands in the pocket such as disclosed in U.S. Pat. No. 4,624,098. Accordingly, the device now in conventional use for such threaded plastic caps, at least when used on plastic containers, is a anti-rotation device developed by Metal Box p.l.c. This device includes a capper pocket that has an arbitrarily designated forward converging surface and a rearward converging surface. The forward converging surface has backwardly facing teeth which oppose the tightening direction of rotation of the capper head. The rearward converging surface is smooth and acts, in conjunction with rear guide, as a cam surface to drive the container neck against the teeth of the forward converging surface. This device has several limitations. For instance, the toothed anti-rotation device is limited to plastic bottle applications in which the backwardly facing teeth can grip and permanently indent the surface without fracturing the container. In glass bottles, the shock loading when the backwardly facing teeth grip the neck could result in container fracture. Furthermore, although the forward and rearward converging surfaces are designed to be easily replaced, the replacement cost for each capper pocket approaches several hundred dollars and is relatively expensive. In addition, the device is functionally limited. Not all containers have straight neck portions underneath the threads. Many bottle designs curve or taper the neck, and when this occurs, the backwardly facing teeth make detrimental point contact with the container neck. More significantly, the diameter of the neck portions of a plastic container, whether tapered or straight, typically varies from the nominal dimension. The dimensional variation means that for some containers, the neck of the container will be cocked or wrenched into point indentation contact with the backwardly facing teeth as the cap is tightened. This will mark or score the neck wall and such marking is, of course, aggravated if the neck tapers and is not straight. Since the plastic used to manufacture the container is somewhat permeable, the scoring permits the gas of a carbonated beverage within the container to more easily permeate through the plastic, contributing to a “flat” beverage. More critical, though, is that the neck marking or scoring acts as a stress riser to cause an occasional container failure. This is unacceptable. Additionally, the container is aesthetically marred.
These problems were successfully addressed in U.S. Pat. No. 4,939,890, wherein an upwardly directed knife is used to prevent the rotation of the container during the capping process. The knife engaged the lower surface of a circular flange at the bottom of the threaded neck of a plastic container to prevent rotation of the plastic container. A mechanism for externally applying a downward force on the body of the container being capped, which force was independent of the downward force created by the capping operation, was used during the capping process. This anti-spin or anti-rotation mechanism has been successful. The anti-rotation device of U.S. Pat. No. 4,939,890 is the most successful arrangement for applying plastic threaded safety caps onto the top of plastic containers where the caps do not require heat to set or position the lower lock band around the neck of the container.
Although the capping mechanism disclosed in U.S. Pat. No. 4,939,890 addressed many of the past deficiencies of past capping mechanisms, the improved capping mechanism required a mechanism for exerting a downward force on the container which was expensive and was dependent upon certain structural characteristics at the upper portion of the container itself. Changes in container configuration often require a new force-exerting mechanism. In addition, the use of the knife slightly disfigured the plastic containers, thereby making the containers less aesthetically pleasing to the consumer. U.S. Pat. Nos. 5,934,042; 5,826,400; 5,816,029; and 5,398,485 disclose anti-rotation mechanisms that address these issues. These patents disclose an anti-rotation mechanism used on a capping machine, which accomplishes the results of the anti-rotation arrangement disclosed in U.S. Pat. No. 4,939,890, but which does not rely upon developing downward frictional force on the top of the container during the capping operation.
The anti-rotation devices disclosed in U.S. Pat. Nos. 5,934,042; 5,826,400; 5,816,029; and 5,398,485, which are incorporated herein by reference, are particularly applicable for use with a plastic container having a pedaloid base (e.g. base with multiple legs), which is somewhat standard in the soft drink industry. These bases include a plurality of downwardly extending feet or pads, generally four or five, separated by diverging recesses. The plastic containers with pedaloid bases are capped in standard machines having a lower plate rotated with the capping heads and having contoured recesses or nests directly aligned with the capping heads and pockets of the rotating star wheel. A plurality of specially contoured recesses that match the pedaloid base configuration are used to receive the bases of the containers as the containers are moved by the star wheel. Since the containers rest upon the lower circular wear plate or ring and are held within a contoured nest on the plate, rotation of the containers is prevented by an interference between the lower wear plate and the bottom, or base, of the container. This arrangement is completely different from the concept of increasing the friction at the top of the container or otherwise preventing rotation of the container by frictional force.
The provision of a lower circular wear plate with machined recesses, each matching the contour of a pedaloid base of the plastic containers, can be expensive. Each of the contoured recesses must be specially produced and accurately matched with respect to the actual shape of each pedaloid base of the container being processed. Consequently, each container required its own lower support wear plate. Indeed, when the filled containers being capped are changed from a four pad pedaloid base to a five pad pedaloid base, a completely new, specially machined plate for supporting the pedaloid bases must be assembled onto the machine. This arrangement for providing a plate rotatable with the star wheel for supporting the lower pedaloid bases of the container demanded a plate which must be accurately machined for use with specific star wheels. Another anti-rotation system included an arrangement for fixing the support member or wear plate in a position spaced from the turret where the containers slide along a rib as the containers are moved around the arcuate path dictated by the movement of the capping head and the star wheel. The rib extended into the lower recess of the pedaloid base of the individual container to prevent rotation of the container as the capping head drove the cap onto the upper threaded neck of the container. By using this construction, a lower support plate carrying the upstanding rib was fixed and did not rotate with the star wheel. The upwardly extending rib prevented rotation of the container during the capping operation. This use of a fixed rib constituted an improvement over other arrangements for using a lower plate with specially contoured recesses to provide interference against rotation of the container by the capping head; however, it required a modification of the capping machine and was expensive to retrofit.
Two anti-rotation mechanisms that overcome these past problems are disclosed in U.S. Pat. Nos. 5,934,042 and 5,816,029. These anti-rotation mechanisms use a standard wear plate of the type rotating with the star wheel of a rotary capping machine and are adapted to accommodate cylindrical containers with an outer cylindrical periphery and a pedaloid base with spaced pads separated by radial recesses extending from a center recess of the base. In the capping machine, the containers are moved along a circular path by a star wheel that has outwardly protruding pockets supporting the necks of the containers while they are supported at the lower position by a rotating wear plate. The wear plate is a flat ring rotated in unison with the star wheel about the machine axis so the containers moving along a given circular path are carried by and supported on the wear plate. The ring constituting the wear plate has an upwardly facing flat surface with a series of container receiving nests movable along the circular path as the ring is rotated by the turret of the capping machine. Each of these nests has an inner area constituting a flat surface and at least one elongated bar-like abutment projecting upwardly from the flat surface of the ring and extending in a direction radial of the inner area of the nests. In practice, two or three of the elongated bar-like abutments project radially outwardly from the inner area defining the nest onto which a container is supported. These radially projecting abutments are faced by an angle defined as 360°/X, wherein X is a number of pads in the pedaloid base. The rib extends into the lower recess of the pedaloid base of the individual container to prevent rotation of the container as the capping head drives the cap onto the upper threaded neck of the container.
Although these prior art capping mechanisms have had excellent success in the bottling of carbonated beverages, problems with damage to the base of the plastic container have resulted when bottling non-carbonated beverages such as water, fruit drinks and the like. Most of the plastic bottles or containers used in the beverage industry are plastic containers made from blow molded polyethylene terephthalate (PET). These plastic containers include “champagne” type bases or bases having a plurality of feet to structurally enhance the base of the plastic bottle or container. Much of the plastic container design has been directed to the carbonated beverage industry. However, the non-carbonated beverage market such as water, sport drinks, fruit drinks and the like has continued to grow. It is not uncommon that plastic containers originally designed for carbonated beverages are used for non-carbonated beverages. However, the use of these plastic containers has been problematic, especially during the bottling of the non-carbonated beverage. The gas in a carbonated beverage exerts a force on interior of the container, thus resisting the deformation or collapse of the base of the container during the capping process. As a result, the base and walls of the plastic container can be made of a thinner material, which is a significant cost savings to the manufacturer. The absence of gas in non-carbonated beverages has resulted in increased deformation and/or damage of the base of the plastic container during the bottling process. In order to address this problem, increased wall thickness for the side walls and base of the plastic container has been used. Although the increased wall thickness of the plastic container reduces the incidence of deformation and/or damage of the base of the plastic container during the bottling process, the increased wall thickness translates into increase material costs. Alternatively, plastic containers that include a plastic base attachment have also been used to address this problem. However, the use of the plastic base attachment also increases the cost of the container. Bottling manufacturers that bottle both carbonated and non-carbonated beverages must now maintain additional inventory of various bottle or container configurations and thicknesses. In addition, plastic containers that do not have a pedaloid base could not be used in a bottling apparatus that had anti-wear plates to prevent rotation of the container. For instance, containers having flat bases or champagne type bases were not prevented from rotation on such wear plates.
Another aspect of the bottling process relates to conveying the bottles to and from the capping machine. As can be appreciated, large volumes of bottles must be fed to first the filling portion of the process and then later to the capping machine. Furthermore, due to the scale of these bottling operations and the sizes of the machines used therein, the conveying portion of the bottling process can be significant. Therefore, it is advantageous to provide low cost methods to convey both the unfilled and the filled bottles to and from the bottling apparatuses. As stated above, downtime can be costly which necessitates quick changeovers from one bottle size to the next or from carbonated beverages to non-carbonated beverages. As can also be appreciated, a changeover which necessitates a modification to the conveying system can be costly in both man hours used to make the changeover and loss profits for the time in which the operation is shut down. Thus, it is preferred that modifications to the conveying system be minimized from one bottle to the next.
It has been found that air powered conveyors can be used to inexpensively convey the empty bottles to the filling and capping machines. Due to the lightweight plastic materials used in the construction of these bottles, air pressure can effectively move a large number of bottles if the air is properly directed. The use of pressurized air to convey the empty bottles is disclosed in U.S. Pat. Nos. 4,284,370; 5,161,919 and 5,437,521, which are incorporated herein by reference for showing air conveying systems. However, these air conveying systems must effectively utilize the neck flange of the bottle and the outer configuration of the bottle to support and move the bottle in the desired direction. Modifications to the neck flange and/or bottle configuration can have adverse affects to the effectiveness of the conveying system. In one respect, the air power conveyor systems rely on the neck flange to support the bottle as it is conveyed. The neck flange provides a good support structure and also minimizes the frictional or drag force produced by the supporting structure of the conveying system. Thus, if the neck flange becomes disengaged from the rails of the conveying system, the bottle can become jammed or can fall from the conveying system. Therefore, it is important that the neck flange be configured to reliably maintain the engagement with the conveying rails of the air conveyor at all times to minimize downtime in the conveying process.
Yet another aspect of using an air conveying systems, is the control of the pressurized air. As can be appreciated, the pressurized air will only move the bottles if it engages at least one surface of the bottle. In addition, containing the pressurized air is also a factor. Air escaping from the conveying system can reduce the efficiency of the conveyor. As a result, the tolerances between the rails of conveying system and the outer configuration of the neck of the bottle are a factor in how well the conveyor will move a particular bottle.
In view of the present state of the art for bottling machines, there is a need for a bottling machine that can be used for non-carbonated beverages which resists deformation and/or damage to the base and/or body of the plastic beverage container during the bottling process, and which can be used to inhibit or prevent rotation of a variety of container designs during the bottling and/or capping process. Furthermore, in view of the present state of the art for plastic beverage bottles, there is a need for a plastic beverage container that can be used for non-carbonated beverages which resists deformation and/or damage to the base and/or body of the plastic beverage container during the bottling and conveying processes, and which has substantially the same material cost as standard plastic bottles used for carbonated beverages.